a) Field of the Invention
This disclosure relates generally to engineered wood building materials and, more particularly, to engineered wood rim boards used in light frame construction of buildings.
b) Background
From the 1960s to the present the wood framing industry has evolved where more and more dimensional framing members are being replaced by their engineered lumber counterparts. Engineered Lumber Manufactures have developed a multitude of innovative engineered lumber framing members that improve upon their dimensional lumber predecessors in order to meet the needs required by today's building industry.
Engineered lumber use various types of structural composite lumber such as laminated veneer lumber (“LVL”), parallel strand lumber (“PSL”), laminated strand lumber (“LSL”), oriented strand lumber (“OSL”), glue laminated timber (“gluelam”) to create structural components, such as rim boards and I-joists, designed to meet a corresponding variety of specific structural framing requirements.
Conventional rim board or rim joists used in constructing floor platforms may not be able to carry the structural load above wall openings such as doors and windows by themselves, particularly as the opening width is increased, requiring the use of structural headers.
Likewise, conventional double plates in the top floor of a structure to support ceiling joists and roof rafters may similarly not be able to carry the structural load of the roof, particularly above wall openings such as doors and windows in the top floor.
Moreover, for multi-story light frame construction, the loads that must be carried by the rim boards of lower floors increases as new floors are added during construction.
In the above cases, additional structural elements, such as extra king studs, jamb/jack studs, cripples, structural headers, etc. are used to augment the load-carrying capability over openings and/or for supporting ceiling joists and roof rafters. However, those additional elements add cost and waste. In an effort to reduce cost and waste in light frame construction, techniques known as “advanced framing techniques” have been devised. Advanced framing techniques use a systems approach to the design, engineering, and construction of wood-framed structures to reduce lumber use, minimize wood waste, and maximize a structure's thermal efficiency, while still maintaining the structural integrity and meeting building codes.